Children consider radiation therapy one of the most stressful aspects of having cancer. Although radiation therapy is pain-free, pediatric patients fin it anxiety provoking and difficult due to misunderstandings about radiation therapy, having to transition to an unfamiliar treatment setting and medical team, feeling intimidated by the large and noisy equipment, and being required to remain alone and motionless throughout the procedure. To ensure that children do not move during radiation therapy, sedation might be needed, which invites a host of additional risks and costs. Data indicate that patient preparation programs can improve the success of conducting radiation without sedation and decrease children's and their parents' anxiety. A critical barrier to progress in conducting radiation withot sedation and decreasing children's and their parents' anxiety is that the current standard form of preparation - when provided at all - requires extensive time, space, funding, and personnel; healthcare resources that are increasingly in short supply. Our aims are to (1) develop RadWorld beta: an automated, interactive, engaging, patient-centered, cost- effective, time-efficient, virtual world program to prepare children and their parents for pediatric radiation therapy; (2) develop RadWorld; and (3) evaluate the effectiveness of RadWorld for pediatric radiation therapy preparation. Our team will develop and refine a beta version and a final version of RadWorld via feedback from patient semi-structured interviews, usability testing, and technical analyses. The third aim will be examined with a randomized controlled trial comparison of RadWorld to standard preparation. We expect that children exposed to RadWorld will have more knowledge, less fear and anxiety, fewer sedations, and greater satisfaction with radiation therapy than children receiving standard care. Parents randomized to RadWorld should also have better knowledge, lower fear and anxiety, and higher satisfaction associated with pediatric radiation therapy than parents in the standard care condition. In addition, we hypothesize that RadWorld will be more time- and cost-efficient than standard preparation procedures. Our long-term aims are to expand the scope of RadWorld to other pediatric oncology procedures as well as medical stressors faced by children outside of oncology. Our program of research uses IT to improve the quality, safety, efficiency, and effectiveness of pediatric healthcare.